package controller;

import com.fasterxml.jackson.databind.ObjectMapper;
import model.User;
import model.UserDao;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;


// 实现登录页面
@WebServlet("/login")
public class LoginServlet extends HttpServlet {
    private  ObjectMapper objectMapper = new ObjectMapper();

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        // 1. 获取到请求中的参数
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        if(username == null || "".equals(username) || password == null || "".equals(password)) {
            // 请求内容缺失，登录失败
            resp.setContentType("text/html; charset=utf8");
            resp.getWriter().write("当前的用户名或者密码为空");
            return;
        }
        // 2. 和数据库中的的内容进行比较
        UserDao userDao = new UserDao();
        User user = userDao.selectByName(username);
        if(user == null || !user.getPassword().equals(password)) {
            // 用户没有查到或者密码不匹配，登录失败
            resp.setContentType("text/html;charset=utf8");
            resp.getWriter().write("用户名或密码错误");
            return;
        }
        // 3. 如果比较通过，则创建会话
        HttpSession session = req.getSession(true);
        // 把刚才的用户信息，存储到会话中
        session.setAttribute("user",user);

        // 4. 返回一个重定向报文，跳转到博客列表页
        resp.sendRedirect("blog_list.html");
    }


 //   //  这个方法用来让前端检测当前的登录状态~~~~~~~~~~~~~~~~~~~~~~
    // 1）检测有无会话 2）检测有无属性
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       resp.setContentType("application/json;charset=utf8");
       HttpSession session =  req.getSession(false);

       if(session == null) {
           // 1) 检测有无会话，无说明未登录
           // 创建对象--> 里面为空
           User user = new User();
           resp.getWriter().write(objectMapper.writeValueAsString(user));
           return;
       }
       User user = (User) session.getAttribute("user");
       if(user == null) {
           // 2)虽然有会话，但是会话里如果没有 user 对象，也视为未登录
           user = new User();
           resp.getWriter().write(objectMapper.writeValueAsString(user));
           return;
       }
       // 已经登录的状态！
        // 注意，此处不要把密码返回到前端
        user.setPassword("");
        resp.getWriter().write(objectMapper.writeValueAsString(user));
    }
}
